Microbiological Quality of Australian Beef, Sheep and Pork Carcases, Cuts and Offals.

A one-year survey was undertaken of the microbiological quality of carcases and the derived primal cuts, manufacturing meat and offals at twelve Australian export establishments (six beef, three sheep/lamb and three pork). A total of 27,157 microbiological results for aerobic plate count (APC) and generic Escherichia coli were gathered, 15,155 from beef, 8405 from sheep and 3597 from pig establishments. The mean log10 APCs on beef, sheep and pig carcases were 0.84, 1.60 and 1.30 log10 cfu/cm2, respectively. For primals, the mean log10 APC was higher for beef but was similar for sheep and pork primals, with 'outside' cuts having higher counts. For manufacturing meat, the concentration was 2-3 log10 cfu/g, irrespective of species. The prevalence (%) of generic E. coli from beef, sheep and pork was 2.3, 28.4 and 5.4 on carcases; 7.0, 20.6 and 3.2 on primals; and 5.8, 33.6 and 6.1 on manufacturing meat, respectively. The mean log10 APCs of beef, sheep and pork offal were 3.23, 3.18 and 3.37 log10 cfu/g, with tripes and tongues having APCs 1-2 log10 units higher than organ offals. The results reflect improvements in total bacterial loadings compared with previous national baseline surveys.

Effect of Sampling Plans on the Risk of Escherichia coli O157 Illness.

Australia exports about 150,000 to 200,000 tons of manufacturing beef to the United States annually. Each lot is tested for Escherichia coli O157 using the N-60 sampling protocol, where 60 small pieces of surface meat from each lot of production are tested. A risk assessment of E. coli O157 illness from the consumption of hamburgers made from Australian manufacturing meat formed the basis to evaluate the effect of sample size and amount on the number of illnesses predicted. The sampling plans evaluated included no sampling (resulting in an estimated 55.2 illnesses per annum), the current N-60 plan (50.2 illnesses), N-90 (49.6 illnesses), N-120 (48.4 illnesses), and a more stringent N-60 sampling plan taking five 25-g samples from each of 12 cartons (47.4 illnesses per annum). While sampling may detect some highly contaminated lots, it does not guarantee that all such lots are removed from commerce. It is concluded that increasing the sample size or sample amount from the current N-60 plan would have a very small public health effect.

Risk Assessment of Escherichia coli O157 illness from consumption of hamburgers in the United States made from Australian manufacturing beef.

We analyze the risk of contracting illness due to the consumption in the United States of hamburgers contaminated with enterohemorrhagic Escherichia coli (EHEC) of serogroup O157 produced from manufacturing beef imported from Australia. We have used a novel approach for estimating risk by using the prevalence and concentration estimates of E. coli O157 in lots of beef that were withdrawn from the export chain following detection of the pathogen. For the purpose of the present assessment an assumption was that no product is removed from the supply chain following testing. This, together with a number of additional conservative assumptions, leads to an overestimation of E. coli O157-associated illness attributable to the consumption of ground beef patties manufactured only from Australian beef. We predict 49.6 illnesses (95%: 0.0-148.6) from the 2.46 billion hamburgers made from 155,000 t of Australian manufacturing beef exported to the United States in 2012. All these illness were due to undercooking in the home and less than one illness is predicted from consumption of hamburgers cooked to a temperature of 68 °C in quick-service restaurants.

An Australian national survey of the microbiological quality of frozen boneless beef and beef primal cuts.

The fourth national baseline microbiological survey of Australian beef was conducted in 2011, including frozen boneless beef and, for the first time, samples from selected beef primal cuts. Cartons of frozen boneless beef (n = 1,165) sampled at 29 boning (fabrication) plants were found to have a mean total viable count of 2.2 log CFU/g, and the mean count for the 2.1% of samples with detectable Escherichia coli was 1.3 log CFU/g. The mean total viable counts for striploins (longissimus dorsi, n = 572) and outsides (biceps femoris, n = 572) were 1.3 and 1.5 log CFU/cm(2) respectively. E. coli isolates were obtained from 10.7 and 25.2% of striploins and outsides, respectively, with mean counts of -0.5 and -0.3 log CFU/cm(2) on positive samples. E. coli O157:H7, Salmonella, and Campylobacter were not isolated from any primal cut samples, and Salmonella was not isolated from any of the boneless product (E. coli O157:H7 and Campylobacter were not tested for). Listeria spp. were not detected in any of the boneless product, and one Listeria isolate was obtained on 1 (0.2%) of 572 striploin samples. Coagulase-positive staphylococci were isolated from 3.4% of boneless beef samples, 7.7% of beef striploins, and 8.4% of beef outsides, with positive samples having mean log counts of 1.9 CFU/g, 0.2 CFU/cm(2), and 0.2 CFU/cm(2), respectively.

Vacuum-packed beef primals with extremely long shelf life have unusual microbiological counts.

When vacuum-packed striploins and cube rolls processed by six Australian establishments were stored at 2 0.5°C to determine their shelf life, all product was acceptable organoleptically for at least 26 weeks. The aerobic plate counts and counts of lactic acid bacteria over the storage period did not accord with those established by previous studies, i.e., stationary phase attained at 7 to 8 log CFU/cm(2) after 5 to 8 weeks followed by the development of negative sensory characteristics around 12 to 16 weeks. Rather, counts rarely progressed to 7 log CFU/cm(2) even after 30 weeks. It is believed that the combined effects of meat pH, temperature, and CO(2) concentration may combine to create conditions in which little or no growth occurs.

Performance standards and meat safety--developments and direction.

Performance standards have been developed to express, for regulatory purposes, an acceptable level of food safety afforded by either a product or a process. These performance standards have reflected the development of scientific thought on food safety management through setting of microbiological criteria, implementing hazard analysis critical control point (HACCP) systems, process control and risk-based management. In meat safety management, some performance standards reflect current risk-based thinking which sets objectives and/or criteria and allows freedom on how those objectives/criteria can be met. However, many performance standards do not reflect current thinking and some perpetuate the idea that meat can be consumed with zero risk.

2009 pandemic influenza A (H1N1): pathology and pathogenesis of 100 fatal cases in the United States.

In the spring of 2009, a novel influenza A (H1N1) virus emerged in North America and spread worldwide to cause the first influenza pandemic since 1968. During the first 4 months, over 500 deaths in the United States had been associated with confirmed 2009 pandemic influenza A (H1N1) [2009 H1N1] virus infection. Pathological evaluation of respiratory specimens from initial influenza-associated deaths suggested marked differences in viral tropism and tissue damage compared with seasonal influenza and prompted further investigation. Available autopsy tissue samples were obtained from 100 US deaths with laboratory-confirmed 2009 H1N1 virus infection. Demographic and clinical data of these case-patients were collected, and the tissues were evaluated by multiple laboratory methods, including histopathological evaluation, special stains, molecular and immunohistochemical assays, viral culture, and electron microscopy. The most prominent histopathological feature observed was diffuse alveolar damage in the lung in all case-patients examined. Alveolar lining cells, including type I and type II pneumocytes, were the primary infected cells. Bacterial co-infections were identified in >25% of the case-patients. Viral pneumonia and immunolocalization of viral antigen in association with diffuse alveolar damage are prominent features of infection with 2009 pandemic influenza A (H1N1) virus. Underlying medical conditions and bacterial co-infections contributed to the fatal outcome of this infection. More studies are needed to understand the multifactorial pathogenesis of this infection.

Isolation of Rickettsia parkeri and identification of a novel spotted fever group Rickettsia sp. from Gulf Coast ticks (Amblyomma maculatum) in the United States.

Until recently, Amblyomma maculatum (the Gulf Coast tick) had garnered little attention compared to other species of human-biting ticks in the United States. A. maculatum is now recognized as the principal vector of Rickettsia parkeri, a pathogenic spotted fever group rickettsia (SFGR) that causes an eschar-associated illness in humans that resembles Rocky Mountain spotted fever. A novel SFGR, distinct from other recognized Rickettsia spp., has also been detected recently in A. maculatum specimens collected in several regions of the southeastern United States. In this study, 198 questing adult Gulf Coast ticks were collected at 4 locations in Florida and Mississippi; 28% of these ticks were infected with R. parkeri, and 2% of these were infected with a novel SFGR. Seventeen isolates of R. parkeri from individual specimens of A. maculatum were cultivated in Vero E6 cells; however, all attempts to isolate the novel SFGR were unsuccessful. Partial genetic characterization of the novel SFGR revealed identity with several recently described, incompletely characterized, and noncultivated SFGR, including "Candidatus Rickettsia andeanae" and Rickettsia sp. Argentina detected in several species of Neotropical ticks from Argentina and Peru. These findings suggest that each of these "novel" rickettsiae represent the same species. This study considerably expanded the number of low-passage, A. maculatum-derived isolates of R. parkeri and characterized a second, sympatric Rickettsia sp. found in Gulf Coast ticks.

Rickettsia 364D: a newly recognized cause of eschar-associated illness in California.

BACKGROUND: Four spotted fever group rickettsiae (SFGR) are known to infect humans in the United States. A member of the SFGR designated 364D and detected in Dermacentor occidentalis ticks has not previously been identified as a human pathogen. METHODS: An 80-year-old man from a rural northern California community presented with an eschar on his forearm. A skin punch biopsy of the lesion was evaluated by immunohistochemistry and molecular analysis. Serum specimens obtained from the patient and 3 other area residents with similar illnesses were tested by immunofluorescence and Western immunoblot for antibodies to SFGR. Ticks were collected near the patient's residence and tested for SFGR. RESULTS: Abundant intracellular rickettsiae and fragmented rickettsial antigens were observed in the mononuclear inflammatory infiltrates of the biopsy. Nucleotide sequences of DNA fragments amplified from the biopsy were identical to those of 364D. Convalescent sera from all four patients exhibited high immunoglobulin G titers to Rickettsia rickettsii, Rickettsia rhipicephali, and 364D antigens. Three adult D. occidentalis were positive for 364D, R. rhipicephali, and an unidentified Rickettsia species. CONCLUSIONS: This is the first confirmation of human disease associated with the SFGR 364D, which was likely transmitted by D. occidentalis. Although the patients described here presented with a single cutaneous eschar as the principal manifestation, the full spectrum of illness associated with 364D has yet to be determined. Possible infection with 364D or other SFGR should be confirmed through molecular techniques in patients who present with "spotless" Rocky Mountain spotted fever or have serum antibodies to R. rickettsii with group-specific assays.

Ehrlichia ewingii in an immunocompetent adult.

The third Ehrlichia infection described in humans in the United States is reviewed. This rare zoonosis was first published in 1999. This case report that expands the clinical paradigm is described. A 57-year-old immunocompetent adult, unlike previously published reports, did not cross react with Ehrlichia chaffeensis.

New approaches to detection and identification of Rickettsia africae and Ehrlichia ruminantium in Amblyomma variegatum (Acari: Ixodidae) ticks from the Caribbean.

Imported from Africa in the 1700s and despite frequent modern eradication efforts, Amblyomma variegatum (F.) spread through the Caribbean by cattle transport, small ruminants, and migrating birds. A. variegatum is a vector for Rickettsia africae, the causative agent of African tick bite fever, and Ehrlichia ruminantium, the causative agent of heartwater. We examined 95 A. variegatum and six Rhipicephalus (Boophilus) microplus (Canestrini) collected from cattle at an abattoir in Antigua. Engorged tick extracts adsorbed on Nobotu filter paper strips and new nested polymerase chain reaction (PCR) assays for E. ruminantium and Dermatophilus congolensis were used to evaluate these ticks for the presence of these pathogenic bacteria. Amblyomma ticks (62.4%) contained R. africae DNA by PCR/restriction fragment length polymorphism analysis and DNA sequencing of the OmpA and 17-kDa antigen genes. Twenty Amblyomma and two Rh. microplus contained E. ruminantium DNA. No E. chaffeensis, Anaplasma phagocytophilum, Coxiella burnetii, or D. congolensis DNA was detected in these ticks. The continued presence of Am. variegatum in the Caribbean poses a significant risk of infection in cattle with E. ruminantium and in humans by R. africae. Eradication efforts are essential to prevent the further spread of Am. variegatum.

Quantitative risk assessment of Listeria monocytogenes in ready-to-eat meats in Australia.

Listeria monocytogenes is a food-borne pathogen that can contaminate processed meats and has caused outbreaks in several nations in which processed meats were the vehicle. Due to its ecology, the control of this organism in ready-to-eat meats is difficult. As a first step in improving risk management for this product:pathogen pair in Australia, a stochastic simulation model to predict the numbers of L. monocytogenes likely to be consumed in those products under a wide range of scenarios was developed. The predictions are based on data describing initial contamination levels of both lactic acid bacteria and L. monocytogenes, product formulation, times and temperatures of distribution and storage prior to consumption, and consumption patterns. The model was used to estimate the probable numbers of cases of listeriosis due to processed meats in Australia per year. The model predicted that processed meats could be responsible for up to approximately 40% of cases of listeriosis in Australia, a level considered credible by comparison with available epidemiological data. The reliability of the model, as well as data gaps and further research needs, is discussed.

Rickettsia parkeri in Argentina.

Clinical reports of an eschar-associated rickettsiosis in the Paraná River Delta of Argentina prompted an evaluation of Amblyomma triste ticks in this region. When evaluated by PCR, 17 (7.6%) of 223 questing adult A. triste ticks, collected from 2 sites in the lower Paraná River Delta, contained DNA of Rickettsia parkeri.

Rickettsia parkeri rickettsiosis and its clinical distinction from Rocky Mountain spotted fever.

BACKGROUND: Rickettsia parkeri rickettsiosis, a recently identified spotted fever transmitted by the Gulf Coast tick (Amblyomma maculatum), was first described in 2004. We summarize the clinical and epidemiological features of 12 patients in the United States with confirmed or probable disease attributable to R. parkeri and comment on distinctions between R. parkeri rickettsiosis and other United States rickettsioses. METHODS: Clinical specimens from patients in the United States who reside within the range of A. maculatum for whom an eschar or vesicular rash was described were evaluated by > or =1 laboratory assays at the Centers for Disease Control and Prevention (Atlanta, GA) to identify probable or confirmed infection with R. parkeri. RESULTS: During 1998-2007, clinical samples from 12 patients with illnesses epidemiologically and clinically compatible with R. parkeri rickettsiosis were submitted for diagnostic evaluation. Using indirect immunofluorescence antibody assays, immunohistochemistry, polymerase chain reaction assays, and cell culture isolation, we identified 6 confirmed and 6 probable cases of infection with R. parkeri. The aggregate clinical characteristics of these patients revealed a disease similar to but less severe than classically described Rocky Mountain spotted fever. CONCLUSIONS: Closer attention to the distinct clinical features of the various spotted fever syndromes that exist in the United States and other countries of the Western hemisphere, coupled with more frequent use of specific confirmatory assays, may unveil several unique diseases that have been identified collectively as Rocky Mountain spotted fever during the past century. Accurate assessments of these distinct infections will ultimately provide a more valid description of the currently recognized distribution, incidence, and case-fatality rate of Rocky Mountain spotted fever.

A national survey of the microbiological quality of retail raw meats in Australia.

A national survey of the microbiology of meat (ground beef and diced lamb) at the retail level in Australia was undertaken. For ground beef samples (n = 360), the mean aerobic plate count (APC) was 5.79 log CFU/g, and Escherichia coli was detected in 17.8% of samples; the mean population for these positive samples was 1.49 log CFU/g. Enterobacteriaceae were detected in 96.9% of samples (mean for positive samples, 3.01 log CFU/g), and coagulase-positive staphylococci were detected in 28.1% of samples (mean for positive samples, 2.18 log CFU/g). For diced lamb samples (n = 360), the mean APC was 5.71 log CFU/g, and E. coli was detected in 16.7% of samples (mean for positive samples, 1.67 log CFU/g). Enterobacteriaceae were detected in 91.1% of samples (mean for positive samples, 2.85 log CFU/g), and coagulase-positive staphylococci were detected in 22.5% of samples (mean for positive samples, 2.34 log CFU/g). Salmonella was recovered from 4 (1.1%) of the 360 ground beef samples (isolates were Salmonella Typhimurium phage types), and E. coli O157 was recovered from 1 (0.3%) of 357 samples; Campylobacter and Clostridium perfringens were not recovered from any of the 91 and 94 samples tested, respectively. Salmonella was recovered from 2 (0.6%) of the 360 diced lamb samples (serovars were Salmonella Infantis and Salmonella Typhimurium), Campylobacter was recovered from 1 (1.1%) of 95 samples, and C. perfringens was recovered from 1 (1.1%) of 92 samples.

Rocky Mountain spotted fever in Argentina.

We describe the first molecular confirmation of Rickettsia rickettsii, the cause of Rocky Mountain spotted fever (RMSF), from a tick vector, Amblyomma cajennense, and from a cluster of fatal spotted fever cases in Argentina. Questing A. cajennense ticks were collected at or near sites of presumed or confirmed cases of spotted fever rickettsiosis in Jujuy Province and evaluated by polymerase chain reaction assays for spotted fever group rickettsiae. DNA of R. rickettsii was amplified from a pool of A. cajennense ticks and from tissues of one of four patients who died during 2003-2004 after illnesses characterized by high fever, severe headache, myalgias, and petechial rash. The diagnosis of spotted fever rickettsiosis was confirmed in the other patients by indirect immunofluorescence antibody and immunohistochemical staining techniques. These findings show the existence of RMSF in Argentina and emphasize the need for clinicians throughout the Americas to consider RMSF in patients with febrile rash illnesses.

Effect of incubation temperature on aerobic plate counts of beef and sheep carcasses.

Australian regulations for microbiological testing of carcasses specify a number of incubation temperatures and media for meat processed at both domestic and export establishments. Accordingly, the effect of incubation temperature and media on aerobic plate counts of samples from beef and sheep carcasses was investigated. For both species, aerobic plate counts on Petrifilm incubated at 35 degrees C were significantly lower than those counts on Petrifilm and pour plates incubated at 25 and 30 degrees C, reflecting the inability of many psychrotrophs to grow at 35 degrees C. When samples were taken from carcasses that had been stored in abattoir chillers for periods between 16 h and 5 days, difference between counts at 35 degrees C versus those incubated at 25 and 30 degrees C became greater as the period of refrigerated storage increased. For export beef carcasses, the effect of this difference is minimal, since the vast majority of counts incubated at 35 degrees C are done on carcasses that have been chilled for less than 24 h and will not have a large proportion of psychrotrophs.

Microbial profiles of carcasses and minced meat from kangaroos processed in South Australia.

The microbiological profiles of kangaroo carcasses and minced meat at game meat processing plants in South Australia were determined in surveys undertaken in 2002 and 2004. In 2002 mean values for log(10) total viable counts (TVC) on carcasses at individual plants ranged from 0.9 to 3.9 log(10) cfu/cm(2), with the mean for all plants being 2.3 log(10) cfu/cm(2). In 2004 the between plant range was narrower, by about 1 log unit, and the mean value for carcasses at all plants was 1.2 log(10) cfu/cm(2). Minced kangaroo meat, was sampled in 2002 only. The overall mean log(10) TVC was 3.9 log(10) cfu/g, with mean counts at individual plants ranging from 3.1 to 4.6 log(10) cfu/g. The overall prevalence of E. coli was 70%, with mean numbers of 2.1 log(10) cfu/g on positive samples. Salmonella was not detected in any of 60 samples from carcasses in 2002. However, in 2004 Salmonella was detected in 4/385 samples (1.04%, 95% CI: 0.28%-2.64%). In minced kangaroo meat, Salmonella was detected in 9/50 (18%, 95% CI: 9%-31%) samples. The abdominal cavity, sampled in 2004, was found to be highly contaminated, with E. coli isolated from 46% of samples and the mean number for positive samples being 2.7 log(10) cfu/cm(2); Salmonella was isolated from 14/120 (12%; 95% CI: 6.52%-18.80%) of abdominal cavities. The practice of collecting carcasses together and pushing grouped carcasses into the chiller likely leads to cross contamination of carcasses from the abdominal cavities of others. To align results of sampling by swabbing for domestic purposes with excision sampling, required for export purposes, both methods were used to sample opposite sides of each of the 50 carcasses sampled in 2004. The results obtained with the two methods of sampling were similar.

Gulf Coast ticks (Amblyomma maculatum) and Rickettsia parkeri, United States.

Geographic distribution of Rickettsia parkeri in its US tick vector, Amblyomma maculatum, was evaluated by PCR. R. parkeri was detected in ticks from Florida, Georgia, Kentucky, Mississippi, Oklahoma, and South Carolina, which suggests that A. maculatum may be responsible for additional cases of R. parkeri rickettsiosis throughout much of its US range.

An alternative process for cleaning knives used on meat slaughter floors.

Traditionally on slaughter floors operator knives are cleaned by rinsing in hand wash water at 20-40 degrees C followed by brief immersion in baths termed "sterilisers" which contain water no cooler than 82 degrees C. Under Australian legislation, both domestic and export, it is possible for a meat processing establishment to apply to the Controlling Authority for permission to implement an alternative procedure providing that it is at least the equivalent of that legislated. No firm evidence appears to exist for the 82 degrees C requirement and the possibility of replacing this element of the knife cleaning procedure with an alternative procedure using 60 degrees C water and a longer immersion time was investigated at an abattoir slaughtering cattle and sheep. Knives were tested at a range of work stations located along beef and mutton slaughter floors for Aerobic Plate Counts (APCs) and E. coli. For knives used on the beef chain the mean log APC/cm(2) was 2.18 by the current knife cleaning process and 1.78 by the alternate procedure (P<0.001). Using the current system E. coli was isolated from cleaned knives on 20/230 (8.7%) occasions compared with 21/230 (9.1%) occasions using the alternative system. The mean log E. coli of positive knives was 0.43/cm(2) and 0.61/cm(2) from the current and alternative systems, respectively. On the mutton chain the mean log APC/cm(2) was 1.95 using the current knife cleaning process and 1.69 by the alternative procedure (P=0.014). Using the current system E. coli was isolated from cleaned knives on 24/130 (18.5%) occasions compared with 29/130 (22.3%) occasions using the alternative system. The mean log E. coli of positive knives was 0.90/cm(2) and 0.76/cm(2) from the current and alternative systems, respectively. It is concluded that using two knives alternatively, rinsing them in hand wash water, then immersing them between uses in 60 degrees C water provides a microbiological outcome equivalent to rinsing them and momentary dipping in 82 degrees C water.